I like to make stuff. I’m also cheap (right, so that’s why I got a BMW motorcycle?)! I’m going to step through how I made a set of mounts to attach 20 millimeter ammo cans to the factory pannier racks on a 2015 BMW F 800 GS Adventure. I found my ammo cans from a local Craigslist seller. If you are interested, search “large ammo can” on seattle.craigslist.com. They were $30 each and located in Tumwater. The cans are approx 8-3/8″ x 18-5/8″ x 14-7/16″ and weigh about 20 lbs each. I figure this is about comparable to a 36 liter pannier. He had a great inventory of all sorts of surplus ammo cans of various sizes. I painted mine black on the outside and silver (to make it easier to find stuff) on the inside.
My first step was make a sheet metal bender to make the 6 bends I needed. I have a few other projects that I will be using it for. I had a good sized chunk of 8″ channel iron.
I made a few test bends in some scrap I had. The “triangle” for the left side will be the trickiest. I had a few small pieces of 16 ga steel and a few pieces of aluminum. I liked how the aluminum bent and it’s weight, but I’m not able to weld it.
The most difficult part of the project was figuring out how the tabs that will engage the factory rack would be made and how the boxes would be locked to the rack frame. I took some pictures of the factory boxes on a bike at work.
I decided to make the mounts out of 16 ga. It will be heavier but a bit stronger than 18 ga. I thought about getting a bead roller and trying to add some strength that way, but that would be another learning curve. I started with the easier bends (the right side), before trying the left. My bender was just small enough to be able to make the “triangle” on the left mount but I had to take the bender apart to get the steel back out.
I made the tabs by cutting a rectangle in half so that the angle would be close the angle of the ears on the rack. I didn’t want to have to measure and guess each tab location so I took the rack frames off the bike and used them as jigs. This mostly worked. I should have double checked fit a few more times while I was finishing the welds.
The last thing to figure out was the method and location of the “locking” mechanism. I really like the quick release design of the factory boxes. The factory latch also works as the weak point if the boxes are hit hard, allowing the box to pop off with out bending the frame. I ended up just making a clamp that attaches from the inside with a T-handle bolt.
After painting the mounts to match the boxes, I installed them to the boxes with 4 stainless steel #10 cap screws per box. Since I will mainly be using these for around town and will likely switch to soft luggage for any long trips that see off-pavement I think the 4 screws will be enough. In addition, there is the 1/4 stainless bolt holding them to the frame.
Here they are all mounted up.
I installed some of the DOT reflector tape that is used on commercial trucks and trailers. This should help with visibility from the back.
Total cost was approximately $130:
- $60 for both boxes;
- $20 for metal, (I got a full sheet of 16 ga sheet metal for $80 but used less than a quarter of it);
- $30 for various bolts and hardware, and;
- $20 for 4 keyed alike locks.